Radiotelephony.



C. R. ENGLUND.

RADIOTELEPHONY.

APPLICATION mm mm. 29. mo.

fi ,245 #446. Patented Nov. 6, 1917.

a. moraine, or

a I r a moonro a m tpectdoaiden at he tan a p t t Patented hot, n, lhll;

application died ttareh ht, ram. tame.- tie. eater To all whom a mayconcern:

Be it hown that l, Cam. h. European, a citizen of the United States,residing at East Orange, in the count of Ema and t State of New Jersey,have invented certain new and useful Improvements in Radiotele honv, ofwhich the following is a full, car, concise, and exact description.

This invention relates to radio telephony to and in particular to ameans for the transmission of modulated high-frequency warm. lts objectsare to provide more eficient tr.-=ismission and to improve the qualityof the signals received. These objects are actt complished by preventingthe radiation from the antenna of the unmodulated portion of thehigh-frequency wave.

It has been customary'in radio telephony to transmit signals hy ones theprimary to modulating source,tor enamp e microdphene, 'to piroducevariations in the amplitu e of a hlg -trequency wave. As is well known,it the frequency of the carrier wave is U cycles per second and thefrequency oi the at signal to he transmitted h cycles per second, therewill he radiated into the ether a complex wave which is. made up ct thmecomponents at frequencies C-S, t), "CH-h, and these components may heconsiderd to to he radiated independently. lt will he evident that theunmodulated component at carrier trequency E, since it dew not contamthe at frequency S, new not he present in t e antenna, hut may hesupplim tt hy an auxiliary source at the receiving mat on. This methodfor the transmimien ot signals has heen previously propmd and has theadvantage that the d of enerw, due to the presence in the antenna atourto rents oi the m ency G is eliminated. d turtheradvanta is a slightimprovement in the quality o the received si ale.

e present invention provi m another method of eliminating trom theantenna the at unmodulated component ot trequenc t). The manner in whichthis is accomplished will explained in connection with the rawmgs, inwhich Figure l the: a transmlttma station embodying this invento tion,and Fin. 2 a receiving station constructed to coiiperate with thesending mation of hip. 1. This not term a part at this invention.Retention to l ra. l, 1 represents a at lrequeney generator at anysmtahle l tram the station dam and 2 a transformer by means at whichthis generator is connected to the input circuit of a thermionicmodulator 3. d is a micr0- phone circuit which, by means of transformer5, is also conn cted to the input circuit of the modulator 3. The outputcircuit of this modulator, in which there will appear the high-frequencywaves of modulated amplitude, contains one winding of the transformer 6whose other winding is conto nmted to the network 7, 8, 9, 10. In thisnetwork 7, 8 and 9 are resistances, and 110 is a branch containing aninductance coil and a condenser by which it may be tuned. Tn practice,the network is so adjumed that at the carrier frequency C the potentialdiflerencehetween the common point of t, 8 and that of 9 and 10 is equalto zero, and consequently at that frequency no current appears in therimarv of the transformer ll. The secon ary circuit of transformer 6 andthe primary circuit of transformer ll are therefore conjugate at thecarrier frequency. On the other hand. if the frequency is diderent fromthat of the generator l, the hridae network 7, 8. 9, 10 becomesunhalanmd and these windings are no longer conjugate. By thisarrangement, therefore, currents of frequency diflerent carrierfrequency produce an eftent upon the input circuit of the amplifiers 12,which edect can he produced only when the wave of carrier frequency isbeing modulated, that is, when speech is bei transmitted. The outptcircuit of amplifiers 12 is connected through a transformer to common inat circuit of the power ampl here it w use common output commit an eculed to the radiating antenna it. lt will he clear that current can notin this antenna only when the were ot carrier frequency is heinamodulated.

Referring to Fin. 2, l6 rcpt-mute a receiving antenna to which iscoupled the tuned circuit it. This tuned circuit is connected to theinput side eta thermionic detector 118 whose output circuit contains atranslation device 19 such as a telephone receiver. Since the componentof trequency C has heen eliminaM h mn the radiating wave, it will he rto supply waves ot this that at the itceivrna mation, and this isaccomplished by nuns ol the auailiary generator to in circuit with n mil21 Wham .1 a he coupled to W. circuit M0 roe 17 of the receivingstation. ile this invention has been shown as applied to a wirelesssignaling system, it is to be understood that it may be equally wellapplied to signalin over wires in which modulated highrequencyoscillations are uwd.

at is claimed is:

1. A radio transmitting system comprising in combination, means forproducing oscillations of carrier frequency, means for modulatin saidoscillations in accordance with si is. s to be transmitted, two circuitsmutual y conjugate to oscillations of carrier frequency, one of saidcircuits being connocted to said modulating means, and a transmittingcircuit connected to the other of id con ugate circuits.

2. A radio transmitting system comprisin in combination, means forproducing osc' ations of carrier 'frequency, means for modulatin saidoscillations in accordance with signa s to be transmitted, a networkincluding two branches mutually coniugate to oscillations ofcarrier-frequency, said KIT-al.11- lating means being associated withone of said conjugate branches and a transmitting circuit associatedwith the other of said conjugate branch 3. A radio tratting systemcomprising in combination, means for producing oscillations, means formodulating said oscillations in accordance with si ale to be tted, twocircuits mutua conjugate at the frequency of said oscillations one of idcircuits be connected to mi modulating means, am lifying means connectedto the other of said conjugate circuits, and a transmitting circuitconnected to said am plifying means.

4. In a high-frequency signaling system, means for producingoscillations of carrier frequency, means for modulating saidoscillations in accordance with signals to be transmitted, two circuitsmutual y conjugate to oscillations of carrier frequency, one of saidcircuits being connected to said modulating means, and the other of saidcircuits being connected to a transmitting circuit, in combination witha receiving station comprising a receiving circuit and a source of"oscillations of carrier frequency.

5. In a high-'frequency signaling system, a transmitting stationcomprising means for producing oscillations of carrier frequency, meansfor modulating said oscillations in accordance with signals to betransmitted, two circuits mutually conjugate to oscillations of thecarrier frequency, one of said circuits being connected to saidmodulating means,

and the other of said circuits being connected to a transmittingcircuit, in combination with a receivin station comprisin a receivincircuit, a coal source oi osci lations 0 carrier frequency, and meansfor combining the received oscillations and the locally generatedoscillations.

In witness whereof, I hereunto subscribe my name this 28th day of March,A. D. 1916.

CARL R. ENGLUND.

